Found my own answer in http://www.fai.org/sporting_code/sc3.=ADpdf
section 4.4.7.

Basically electronic flight recorders are 24 months between
calibrations (before the flight) or 2 months afterwards. The times for
mechanical devices is 12 months and 1 month respectively.

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4=2E4.7 Barograph calibration period
Barograph calibrations are required to ensure that the measurement of
baro-metric
pressure and time are checked against, and corrected as necessary, to
official standards. For altitude and gain of height records, both (a)
AND (b) cali-brations
below are required, and the least favourable calibration of the two
shall be used making the calculations for the record. For badges, start
height
verification, and altitude difference calculation, either (a) OR (b)
are required.

a=2E PRIOR TO THE FLIGHT
The calibration used must have been performed within 12 months prior to
the
flight or, for IGC-approved electronic barographs and FRs, 24 months.

b=2E AFTER THE FLIGHT
The calibration used must have been performed within one month after
the
flight or, for IGC-approved electronic barographs and FRs, two months.
(AL5)