Certificar el mes frente a las mediciones

Record what was executed against each partida for the period as a percentage of its contract quantity. The earned quantity follows from that percentage and the design quantity, and the earned amount from the same percentage and the position total, so one honest number per line produces the whole valuation.

Por que: A certificación built from a single project percentage cannot be checked and therefore cannot be approved without a conversation. Measured line by line, the disagreement is about one partida rather than about the whole month, and the rest of the money moves while that one is settled.

Read the valuation back against the bill and check the rates it used are the contract rates. Where a partida has been measured past the quantity the contract carries, deal with it as a change to the position with an order behind it rather than as a larger figure on the same line.

Por que: An exceso de medición certified quietly is one the client can refuse at the final account, months after the work was built and paid for down the chain. Raising it as a change while it is small is the only version of that conversation where you are not asking to be paid for work already done.

Route the certificación to the dirección facultativa, and to whoever the contract adds after them. Keep the approval date, because the invoice follows the approval and the payment clock runs from there, so an approval that slips moves everything behind it.

Por que: Approval sitting in an inbox is the most common reason a payment is late, and it is invisible while it is happening because nobody has refused anything. A route with a date on each hop turns that into a question with an owner instead of a monthly complaint.

Raise the invoice against the approved certificación, carrying retención and any deduction the contract provides for, and reference the certificación on it. Between businesses the invoice usually carries inversión del sujeto pasivo rather than a rate, so the customer accounts for the tax and the invoice has to say so on its face.

Por que: A demand for a figure nobody approved is one that will be returned, and the clock does not start on a returned document. Matching it to the certificación also means the accounts and the valuation tell the same story at year end without anybody reconciling them by hand.

Open a clock over the invoice starting from the invoice date, under Ley 3/2004. Payment falls due 30 days later, and the clock records that date rather than leaving it to be worked out when somebody asks. Thirty days between businesses by default, extendable to sixty by express agreement and no further unless the term is not grossly unfair. On a public contract read the periods the LCSP fixes against the date it gives you.

Por que: The single most expensive mistake in interim payment is starting the count on the wrong event, because every deadline behind it inherits the error and none of them look wrong. Anchoring on the invoice date once makes the whole chain checkable. Interest runs at the European Central Bank reference rate plus eight points from the day it is missed. Late payment is normal in this market and interest is almost never claimed, which is precisely why it keeps happening.